Spectrometer, and spectrometer production method

ABSTRACT

A spectrometer includes a light detection element provided with a light passing part and a light detection part, a support fixed to the light detection element such that a space is formed between the light passing part and the light detection part, a first reflection part provided in the support and configured to reflect light passing through the light passing part in the space, a second reflection part provided in the light detection element and configured to reflect the light reflected by the first reflection part in the space, and a dispersive part provided in the support and configured to disperse and reflect the light reflected by the second reflection part to the light detection part in the space.

TECHNICAL FIELD

The present invention relates to a spectrometer which disperses anddetects light, and a method for manufacturing the spectrometer.

BACKGROUND ART

For example, Patent Literature 1 discloses a spectrometer including alight entrance part, a dispersive part for dispersing and reflectinglight incident thereon from the light entrance part, a light detectionelement for detecting the light dispersed and reflected by thedispersive part, and a box-shaped support for supporting the lightentrance part, dispersive part, and light detection element.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Publication No.2000-298066

SUMMARY OF INVENTION Technical Problem

The above-described spectrometer requires further miniaturization inresponse to expansion of use. However, as the spectrometer is furtherminiaturized, detection accuracy of the spectrometer more easilydecreases due to various causes.

It is therefore an object of the present invention to provide aspectrometer which can attempt miniaturization while suppressing adecrease in detection accuracy, and a method for manufacturing aspectrometer capable of easily manufacturing such a spectrometer.

Solution to Problem

The spectrometer in accordance with one aspect of the present inventionincludes a light detection element provided with a light passing partand a light detection part, a support fixed to the light detectionelement such that a space is formed between the light passing part andthe light detection part, a first reflection part provided in thesupport and configured to reflect light passing through the lightpassing part in the space, a second reflection part provided in thelight detection element and configured to reflect the light reflected bythe first reflection part in the space, and a dispersive part providedin the support and configured to disperse and reflect the lightreflected by the second reflection part to the light detection part inthe space.

In the spectrometer, an optical path from the light passing part to thelight detection part is formed in the space which is formed by the lightdetection element and the support. In this way, miniaturization of thespectrometer may be attempted. Further, the light passing through thelight passing part is reflected by the first reflection part and thesecond reflection part in sequence, and enters the dispersive part. Inthis way, an incident direction of the light entering the dispersivepart and a divergence or convergence state of the light may be easilyadjusted. Thus, even when the length of the optical path from thedispersive part to the light detection part is short, the lightdispersed by the dispersive part may be accurately concentrated on apredetermined position of the light detection part. Therefore, thespectrometer may attempt miniaturization while suppressing a decrease indetection accuracy.

In the spectrometer in accordance with one aspect of the presentinvention, the light passing part, the first reflection part, the secondreflection part, the dispersive part, and the light detection part maybe arranged along a reference line when viewed in an optical axisdirection of the light passing through the light passing part, thedispersive part may have a plurality of grating grooves arranged alongthe reference line, and the light detection part may have a plurality oflight detection channels arranged along the reference line. According tothis configuration, the light dispersed by the dispersive part may bemore accurately concentrated on each of the light detection channels ofthe light detection part.

In the spectrometer in accordance with one aspect of the presentinvention, the first reflection part may be a planar mirror. Accordingto this configuration, when the entrance NA of the light passing throughthe light passing part is made small, and an inequality of “the opticalpath length, from the light passing part to the dispersive part, of thelight having the same spread angle as a spread angle of the lightpassing through the light passing part”>“the optical path length fromthe dispersive part to the light detection part” is satisfied (opticalreduction system), resolving power of the light dispersed by thedispersive part may be increased.

In the spectrometer in accordance with one aspect of the presentinvention, the first reflection part may be a concave mirror. Accordingto this configuration, a spread angle of the light is suppressed by thefirst reflection part, and thus the entrance NA of the light passingthrough the light passing part may be increased to increase sensitivity,and the length of an optical path from the dispersive part to the lightdetection part may be further decreased to further miniaturize thespectrometer.

In the spectrometer in accordance with one aspect of the presentinvention, the light detection element may be provided with a zero-orderlight capture part and configured capture zero-order light in the lightdispersed and reflected by the dispersive part. According to thisconfiguration, it is possible to inhibit the zero-order light frombecoming stray light and detection accuracy from decreasing.

In the spectrometer in accordance with one aspect of the presentinvention, the support may be provided with a wiring electricallyconnected to the light detection part, and an end part of the wiring ona side of the light detection part may be connected to a terminalprovided in the light detection element in a fixed part of the lightdetection element and the support. According to this configuration, theelectrical connection between the light detection part and the wiringmay be secured.

In the spectrometer in accordance with one aspect of the presentinvention, a material of the support may be ceramic. According to thisconfiguration, it is possible to suppress expansion and contraction ofthe support resulting from a temperature change of an environment inwhich the spectrometer is used, etc. Therefore, it is possible tosuppress a decrease in detection accuracy (a shift of a peak wavelengthin light detected by the light detection part, etc.) resulting fromoccurrence of a variance in a positional relationship between thedispersive part and the light detection part.

In the spectrometer in accordance with one aspect of the presentinvention, the space may be airtightly sealed by a package including thelight detection element and the support as components. According to thisconfiguration, it is possible to suppress a decrease in detectionaccuracy resulting from deterioration of a member in the space due tomoisture, occurrence of condensation in the space due to a decrease inambient temperature, etc.

In the spectrometer in accordance with one aspect of the presentinvention, the space may be airtightly seated by a package accommodatingthe light detection element and the support. According to thisconfiguration, it is possible to suppress a decrease in detectionaccuracy resulting from deterioration of a member in the space due tomoisture, occurrence of condensation in the space due to a decrease inambient temperature, etc.

The method for manufacturing a spectrometer in accordance with oneaspect of the present invention includes a first step of preparing asupport provided with a first reflection part and a dispersive part, asecond step of preparing a light detection element provided with a lightpassing part, a second reflection part, and a light detection part, anda third step of fixing the support and the light detection element suchthat a space is formed after the first step and the second step, therebyforming, in the space, an optical path on which light passing throughthe light passing part is reflected by the first reflection part, thelight reflected by the first reflection part is reflected by the secondreflection part, the light reflected by the second reflection part isdispersed and reflected by the dispersive part, and the light dispersedand reflected by the dispersive part enters the light detection part.

In the method for manufacturing the spectrometer in accordance with oneaspect of the present invention, an optical path from the light passingpart to the light detection part is formed in the space only by fixingthe support provided with the first reflection part and the dispersivepart, and the light detection element provided with the light passingpart, the second reflection part, and the light detection part.Therefore, according to the method for manufacturing the spectrometer,it is possible to easily produce the spectrometer which can attemptminiaturization while suppressing a decrease in detection accuracy. Thefirst step and the second step may be implemented in an arbitrary order.

Advantageous Effects of Invention

The present invention can provide a spectrometer which can attemptminiaturization while suppressing a decrease in detection accuracy, anda method for manufacturing a spectrometer capable of easilymanufacturing such a spectrometer.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view of a spectrometer in accordance with afirst embodiment of the invention;

FIG. 2 is a plan view of the spectrometer in accordance with the firstembodiment of the invention;

FIG. 3 is a cross-sectional view of a modified example of thespectrometer in accordance with the first embodiment of the invention;

FIG. 4 is a cross-sectional view of the modified example of thespectrometer in accordance with the first embodiment of the invention;

FIG. 5 is a cross-sectional view of a spectrometer in accordance with asecond embodiment of the invention;

FIG. 6 is a plan view of the spectrometer in accordance with the secondembodiment of the invention;

FIG. 7 is a cross-sectional view of a spectrometer in accordance with athird embodiment of the invention;

FIG. 8 is a cross-sectional view taken along the line VIII-VIII of FIG.7;

FIG. 9 is a cross-sectional view of a spectrometer in accordance with afourth embodiment of the invention;

FIG. 10 is a cross-sectional view taken along the line X-X of FIG. 9;

FIG. 11 is a diagram illustrating a relationship between miniaturizationof a spectrometer and the radius of curvature of the spectrometer; and

FIG. 12 is a diagram illustrating a configuration of a spectrometer inaccordance with a comparative example.

DESCRIPTION OF EMBODIMENTS

In the following, preferred embodiments of the present invention will beexplained in detail with reference to the drawings. In the drawings, thesame or equivalent parts will be referred to with the same signs whileomitting their overlapping descriptions.

First Embodiment

As illustrated in FIGS. 1 and 2, a spectrometer 1A includes a lightdetection element 20, a support 30, a first reflection part 11, a secondreflection part 12, a dispersive part 40, and a cover 50. The lightdetection element 20 is provided with a light passing part 21, a lightdetection part 22, and a zero-order light capture part 23. The support30 is provided with a wiring 13 for inputting/outputting electricsignals to/from the light detection part 22. The support 30 is fixed tothe light detection element 20 such that a space S is formed among thelight passing part 21, the light detection part 22, and the zero-orderlight capture part 23. For example, the spectrometer 1A is formed in ashape of a rectangular parallelepiped, a length of which in each of anX-axis direction, a Y-axis direction, and a Z-axis direction is lessthan or equal to 10 mm. The wiring 13 and the support 30 are configuredas a molded interconnect device (MID).

The light passing part 21, the first reflection part 11, the secondreflection part 12, the dispersive part 40, the light detection part 22,and the zero-order light capture part 23 are arranged side by side alonga reference line RL that extends in the X-axis direction when viewed inan optical axis direction (that is, the Z-axis direction) of light L1passing through the light passing part 21. In the spectrometer 1A, thelight L1 passing through the light passing part 21 is reflected by thefirst reflection part 11 and the second reflection part 12 in sequence,enters the dispersive part 40, and is dispersed and reflected in thedispersive part 40. Then, light L2 other than zero-order light L0 inlight dispersed and reflected in the dispersive part 40 enters the lightdetection part 22 and is detected by the light detection part 22. Thezero-order light L0 in the light dispersed and reflected in thedispersive part 40 enters the zero-order light capture part 23 and iscaptured by the zero-order light capture part 23. An optical path of thelight L1 from the light passing part 21 to the dispersive part 40, anoptical path of the light L2 from the dispersive part 40 to the lightdetection part 22, and an optical path of the zero-order light L0 fromthe dispersive part 40 to the zero-order light capture part 23 areformed in the space S.

The light detection element 20 includes a substrate 24. For example, thesubstrate 24 is formed in a rectangular plate shape using asemiconductor material such as silicone. The light passing part 21 is aslit formed in the substrate 24, and extends in the Y-axis direction.The zero-order light capture part 23 is a slit formed in the substrate24, and extends in the Y-axis direction between the light passing part21 and the light detection part 22. In the light passing part 21, an endpart on an entrance side of the light L1 widens toward the entrance sideof the light L1 in each of the X- and Y-axis directions. In addition, inthe zero-order light capture part 23, an end part on the opposite sidefrom an entrance side of the zero-order light L0 widens toward theopposite side from the entrance side of the zero-order light L0 in eachof the X- and Y-axis directions. When the zero-order light L0 isconfigured to obliquely enter the zero-order light capture part 23, thezero-order light L0 entering the zero-order light capture part 23 may bemore reliably inhibited from returning to the space S.

The light detection part 22 is provided on a surface 24 a of thesubstrate 24 on the space S side. More specifically, the light detectionpart 22 is put in the substrate 24 made of the semiconductor materialrather than being attached to the substrate 24. That is, the lightdetection part 22 includes a plurality of photodiodes formed in a firstconductivity type region inside the substrate 24 made of thesemiconductor material and a second conductivity type region providedwithin the region. For example, the light detection part 22 isconfigured as a photodiode array, a C-MOS image sensor, a CCD imagesensor, etc., and has a plurality of light detection channels arrangedalong the reference line RL. Lights L2 having different wavelengths arelet into the respective light detection channels of the light detectionpart 22. A plurality of terminals 25 for inputting/outputting electricsignals to/from the light detection part 22 is provided on the surface24 a of the substrate 24. The light detection part 22 may be configuredas a surface-incident photodiode or a back surface-incident photodiode.For example, when the light detection part 22 is configured as thesurface-incident photodiode, the light detection part 22 is positionedat the same height as that of a light exit of the light passing part 21(that is, the surface 24 a of the substrate 24 on the space S side). Inaddition, for example, when the light detection part 22 is configured asthe back surface-incident photodiode, the light detection part 22 ispositioned at the same height as that of a light entrance of the lightpassing part 21 (that is, a surface 24 b of the substrate 24 on theopposite side from the space S side).

The support 30 has a base wall part 31, a pair of side wall parts 32,and a pair of side wall parts 33. The base wall part 31 opposes thelight detection element 20 in the Z-axis direction through the space S.A depression 34 open to the space S side, a plurality of projections 35protruding to the opposite side from the space S side, and a pluralityof through holes 36 open to the space S side and the opposite side fromthe space S side are formed in the base wall part 31. The pair of sidewall parts 32 opposes each other in the X-axis direction through thespace S. The pair of side wall parts 33 opposes each other in the Y-axisdirection through the space S. The base wall part 31, the pair of sidewall parts 32, and the pair of side wall parts 33 are integrally formedusing ceramic such as AlN or Al₂O₃.

The first reflection part 11 is provided in the support 30. Morespecifically, the first reflection part 11 is provided on a flatinclined surface 37 inclined at a predetermined angle in a surface 31 aof the base wall part 31 on the space S side with a molded layer 41interposed therebetween. For example, the first reflection part 11 is aplanar mirror including a metal evaporated film of Al, Au, etc. andhaving a mirror surface. The first reflection part 11 reflects the lightL1 passing through the light passing part 21 to the second reflectionpart 12 in the space S. The first reflection part 11 may be directlyformed on the inclined surface 37 of the support 30 without the moldedlayer 41 interposed therebetween.

The second reflection part 12 is provided in the light detection element20. More specifically, the second reflection part 12 is provided in aregion between the light passing part 21 and the zero-order lightcapture part 23 on the surface 24 a of the substrate 24. For example,the second reflection part 12 is a planar mirror including a metalevaporated film of Al, Au, etc. and having a mirror surface. The secondreflection part 12 reflects the light L1, which is reflected by thefirst reflection part 11, to the dispersive part 40 in the space S.

The dispersive part 40 is provided in the support 30. Details thereofare described below. That is, the molded layer 41 is disposed to coverthe depression 34 on the surface 31 a of the base wall part 31. Themolded layer 41 is formed into a film along an inner surface 34 a of thedepression 34. For example, a grating pattern 41 a corresponding to ablazed grating having a serrated cross section, a binary grating havinga rectangular cross section, a holographic grating having a sinusoidalcross section, etc. is formed in a predetermined region of the moldedlayer 41 corresponding to a spherical region on the inner surface 34 a.For example, a reflecting film 42 including a metal evaporated film ofAl, Au, etc. is formed on the molded layer 41 to cover the gratingpattern 41 a. The reflecting film 42 is formed along a shape of thegrating pattern 41 a. A surface of the reflecting film 42, which isformed along the shape of the grating pattern 41 a, on the space S sideserves as the dispersive part 40 in the form of a reflection grating.The molded layer 41 is formed by pressing a mold die against a moldingmaterial (e.g., photocuring epoxy resins, acrylic resins, fluorine-basedresins, silicone, and replica optical resins such as organic/inorganichybrid resins) and curing the molding material (by photocuring orthermal curing using UV light, etc.) in this state.

As described in the foregoing, the dispersive part 40 is provided on theinner surface 34 a of the depression 34 in the surface 31 a of the basewall part 31. The dispersive part 40 has a plurality of grating groovesarranged along the reference line RL, and disperses and reflects thelight L1, which is reflected by the second reflection part 12, to thelight detection part 22 in the space S. The dispersive part 40 is notrestricted to a dispersive part directly formed in the support 30 asdescribed above. For example, the dispersive part 40 may be provided inthe support 30 by attaching a dispersive element, which has thedispersive part 40 and a substrate on which the dispersive part 40 isformed, to the support 30.

Each wiring 13 has an end part 13 a on the light detection part 22 side,an end part 13 b on the opposite side from the light detection part 22side, and a connection part 13 c. The end part 13 a of each wiring 13 ispositioned on an end surface 32 a of each side wall part 32 to opposeeach terminal 25 of the light detection element 20. The end part 13 b ofeach wiring 13 is positioned on a surface of each projection 35 in asurface 31 b on the opposite side from the space S side in the base wallpart 31. The connection part 13 c of each wiring 13 reaches the end part13 b from the end part 13 a on a surface 32 b of each side wall part 32on the space S side, the surface 31 a of the base wall part 31, and aninner surface of each through hole 36. In this way, when the wiring 13encloses a surface of the support 30 on the space S side, deteriorationof the wiring 13 may be prevented.

For example, the terminal 25 of the light detection element 20 and theend part 13 a of the wiring 13 opposing each other are connected to eachother by a bump 14 made of Au, solder, etc. In the spectrometer 1A, thesupport 30 is fixed to the light detection element 20, and a pluralityof wirings 13 is electrically connected to the light detection part 22of the light detection element 20 by a plurality of bumps 14. In thisway, the end part 13 a of each wiring 13 is connected to each terminal25 of the light detection element 20 in a fixed part of the lightdetection element 20 and the support 30.

The cover 50 is fixed to the surface 24 b of the substrate 24 of thelight detection element 20 on the opposite side from the space S side.The cover 50 has a light transmitting member 51 and a light shieldingfilm 52. For example, the light transmitting member 51 is formed in arectangular plate shape using a material which transmits the light L1therethrough, examples of which include silica, borosilicate glass(BK7), Pyrex (registered trademark) glass, and Kovar glass. The lightshielding film 52 is formed on a surface 51 a of the light transmittingmember 51 on the space S side. A light transmitting opening 52 a isformed in the light shielding film 52 to oppose the light passing part21 of the light detection element 20 in the Z-axis direction. The lighttransmitting opening 52 a is a slit formed in the light shielding film52, and extends in the Y-axis direction. In the spectrometer 1A, anentrance NA of the light L1 that enters the space S is defined by thelight transmitting opening 52 a of the light shielding film 52 and thelight passing part 21 of the light detection element 20.

When an infrared ray is detected, silicon, germanium, etc. is effectiveas a material of the light transmitting member 51. In addition, thelight transmitting member 51 may be provided with an AR (AntiReflection) coat, and may have such a filter function as to transmittherethrough only a predetermined wavelength of light. Further, forexample, a black resist, Al, etc. may be used as a material of the lightshielding film 52. Here, the black resist is effective as the materialof the light shielding film 52 from a viewpoint that the zero-orderlight L0 entering the zero-order light capture part 23 is inhibited fromreturning to the space S.

For example, a sealing member 15 made of resin, etc. is disposed amongthe surface 24 a of the substrate 24, the end surface 32 a of each sidewall part 32, and the end surface 33 a of each side wall part 33. Inaddition, for example, a sealing member 16 made of glass beads, etc. isdisposed inside the through hole 36 of the base wall part 31, and theinside of the through hole 36 is filled with a sealing member 17 made ofresin. In the spectrometer 1A, the space S is airtightly sealed by apackage 60A that includes the light detection element 20, the support30, the cover 50, and the sealing members 15, 16, and 17 as components.When the spectrometer 1A is mounted on an external circuit board, theend part 13 b of each wiring 13 functions as an electrode pad. The lightpassing part 21 and the zero-order light capture part 23 of thesubstrate 24 may be airtightly sealed by filling the light passing part21 and the zero-order light capture part 23 of the substrate 24 withlight transmitting resin in place of disposing the cover 50 on thesurface 24 b of the substrate 24. In addition, for example, the insideof the through hole 36 of the base wall part 31 may be filled with onlythe sealing member 17 made of the resin without disposing the sealingmember 16 made of the glass beads, etc.

As described in the foregoing, in the spectrometer 1A, an optical pathfrom the light passing part 21 to the light detection part 22 is formedinside the space S which is formed by the light detection element 20 andthe support 30. In this way, miniaturization of the spectrometer 1A maybe attempted. Further, the light L1 passing through the light passingpart 21 is reflected by the first reflection part 11 and the secondreflection part 12 in sequence, and enters the dispersive part 40. Inthis way, an incident direction of the light L1 entering the dispersivepart 40 and a divergence or convergence state of the light L1 may beeasily adjusted. Thus, even when the length of the optical path from thedispersive part 40 to the light detection part 22 is short, the light L2dispersed by the dispersive part 40 may be accurately concentrated on apredetermined position of the light detection part 22. Therefore, thespectrometer 1A may attempt miniaturization while suppressing a decreasein detection accuracy.

In addition, in the spectrometer 1A, the light passing part 21, thefirst reflection part 11, the second reflection part 12, the dispersivepart 40, and the light detection part 22 are arranged along thereference line RL when viewed from the optical axis direction of thelight L1 passing through the light passing part 21. Further, thedispersive part 40 has the plurality of grating grooves arranged alongthe reference line RL, and the light detection part 22 has the pluralityof light detection channels arranged along the reference line RL. Inthis way, the light L2 dispersed by the dispersive part 40 may be moreaccurately concentrated on each of the light detection channels of thelight detection part 22.

In addition, in the spectrometer 1A, the first reflection part 11 servesas the planar mirror. In this way, when the entrance NA of the light L1passing through the light passing part 21 is made small, and aninequality of “the optical path length, from the light passing part 21to the dispersive part 40, of the light L1 having the same spread angleas a spread angle of the light L1 passing through the light passing part21”>“the optical path length from the dispersive part 40 to the lightdetection part 22” is satisfied (optical reduction system), resolvingpower of the light L2 dispersed by the dispersive part 40 may beincreased. Details thereof are described below. That is, when the firstreflection part 11 is a planar mirror, the dispersive part 40 isirradiated with the light L1 while the light L1 spreads. For thisreason, the entrance NA of the light L1 passing through the lightpassing part 21 needs to be made small from a viewpoint that a region ofthe dispersive part 40 is inhibited from widening and a viewpoint that alength at which the dispersive part 40 concentrates the light L2 on thelight detection part 22 is inhibited from becoming longer. Therefore,resolving power of the light L2 dispersed by the dispersive part 40 maybe increased by reducing the entrance NA of the light L1 and setting anoptical reduction system.

In addition, in the spectrometer 1A, the light detection element 20 isprovided with the zero-order light capture part 23 that captures thezero-order light L0 in light dispersed and reflected by the dispersivepart 40. In this way, it is possible to inhibit the zero-order light L0from becoming stray light due to multiple reflections, etc. anddetection accuracy from decreasing.

In addition, in the spectrometer 1A, the support 30 is provided with thewiring 13 electrically connected to the light detection part 22. Inaddition, the end part 13 a of the wiring on the light detection part 22side is connected to the terminal 25 provided in the light detectionelement 20 in the fixed part of the light detection element 20 and thesupport 30. In this way, it is possible to secure the electricalconnection between the light detection part 22 and the wiring 13.

In addition, in the spectrometer 1A, a material of the support 30 isceramic. In this way, it is possible to suppress expansion andcontraction of the support 30 resulting from a temperature change of anenvironment in which the spectrometer 1A is used, generation of heat inthe light detection part 22, etc. Therefore, it is possible to suppressa decrease in detection accuracy (a shift of a peak wavelength in lightdetected by the light detection part 22, etc.) resulting from occurrenceof a variance in a positional relationship between the dispersive part40 and the light detection part 22. Since the spectrometer 1A isminiaturized, there is concern that a slight change in an optical pathmay greatly affect an optical system, leading to a decrease in detectionaccuracy. For this reason, in particular, as described in the foregoing,when the dispersive part 40 is directly formed in the support 30, it issignificantly important to suppress expansion and contraction of thesupport 30.

In addition, in the spectrometer 1A, the space S is airtightly sealed bythe package 60A that includes the light detection element 20 and thesupport 30 as components. In this way, it is possible to suppress adecrease in detection accuracy resulting from deterioration of a memberin the space S due to moisture, occurrence of condensation in the spaceS due to a decrease in ambient temperature, etc.

In addition, in the spectrometer 1A, the second reflection part 12 isprovided in the light detection element 20. In the light detectionelement 20, the surface 24 a of the substrate 24 on which the secondreflection part 12 is formed is a flat surface. Further, the secondreflection part 12 may be formed in a step of manufacturing the lightdetection element 20. Thus, the second reflection part 12 according to adesired NA may be accurately formed by controlling a shape, an area,etc. of the second reflection part 12.

In addition, in the spectrometer 1A, a flat region (which may beslightly inclined) is present around the depression 34 on the surface 31a of the base wall part 31. In this way, even when reflected light isgenerated in the light detection part 22, the reflected light may beinhibited from reaching the light detection part 22 again. Further, whenthe molded layer 41 is formed on the inner surface 34 a of thedepression 34 by pressing a mold die against resin, and when the sealingmember 15 made of resin is disposed among the surface 24 a of thesubstrate 24, the end surface 32 a of each side wall part 32, and theend surface 33 a of each side wall part 33, the flat region serves as ashelter for surplus resin. In this instance, when the surplus resin isallowed to flow into the through hole 36 of the base wall part 31, forexample, the sealing member 16 made of the glass beads, etc. isunnecessary, and the resin functions as the sealing member 17.

In addition, in a step of manufacturing the spectrometer 1A, asdescribed in the foregoing, the molded layer 41, which is smooth, isformed on the inclined surface 37 of the base wall part 31 using a molddie, and the first reflection part 11 is formed on the molded layer 41.Normally, a surface of the molded layer 41 is less uneven and smootherthan a surface of the support 30, and thus the first reflection part 11having the mirror surface may be more accurately formed. However, whenthe first reflection part 11 is directly formed on the inclined surface37 of the base wall part 31 without the molded layer 41 interposedtherebetween, a molding material used for the molded layer 41 may bereduced, and a shape of the mold die may be simplified. Thus, the moldedlayer 41 may be easily formed.

As illustrated in FIG. 3, for example, the cover 50 may further includea light shielding film 53 made of a black resist, Al, etc. The lightshielding film 53 is formed on a surface 51 b on the opposite side fromthe space S side in the light transmitting member 51. A lighttransmitting opening 53 a is formed in the light shielding film 53 tooppose the light passing part 21 of the light detection element 20 inthe Z-axis direction. The light transmitting opening 53 a is a slitformed in the light shielding film 53, and extends in the Y-axisdirection. In this case, the entrance NA of the light L1 entering thespace S may be more accurately defined using the light transmittingopening 53 a of the light shielding film 53, the light transmittingopening 52 a of the light shielding film 52, and the light passing part21 of the light detection element 20.

In addition, as illustrated in FIG. 4, the cover 50 may further includethe above-described light shielding film 53, and a light transmittingopening 52 b may be formed in the light shielding film 52 to oppose thezero-order light capture part 23 of the light detection element 20 inthe Z-axis direction. In this case, it is possible to more reliablyinhibit the zero-order light L0 entering the zero-order light capturepart 23 from returning to the space S.

In addition, when the spectrometer 1A is produced, the support 30provided with the first reflection part 11 and the dispersive part 40 isprepared (first step), the light detection element 20 provided with thelight passing part 21, the second reflection part 12, and the lightdetection part 22 is prepared (second step), and then the optical pathfrom the light passing part 21 to the light detection part 22 is formedin the space S by fixing the support 30 to the light detection element20 such that the space S is formed (third step). As described above, theoptical path from the light passing part 21 to the light detection part22 is formed in the space S only by fixing the support 30 to the lightdetection element 20. Therefore, according to a method for manufacturingthe spectrometer 1A, it is possible to easily produce the spectrometer1A which can attempt miniaturization while suppressing a decrease indetection accuracy. The step of preparing the support 30 and the step ofpreparing the light detection element 20 may be implemented in anarbitrary order.

In particular, when the spectrometer 1A is produced, in addition to theelectrical connection between the wiring 13 and the light detection part22, fixing of the support 30 to the light detection element 20 andformation of the optical path from the light passing part 21 to thelight detection part 22 are implemented only by connecting the end part13 a of the wiring 13 provided in the support 30 to the terminal 25 ofthe light detection element 20.

Second Embodiment

As illustrated in FIGS. 5 and 6, a spectrometer 1B is mainly differentfrom the above-described spectrometer 1A in that a first reflection part11 is a concave mirror. In the spectrometer 1B, the first reflectionpart 11 is provided in a spherical region on an inner surface 34 a of adepression 34 of a base wall part 31 with a molded layer 41 interposedtherebetween. For example, the first reflection part 11 is a concavemirror which is made of a metal evaporated film of Al, Au, etc. and hasa mirror surface, and reflects light L1 passing through a light passingpart 21 to a second reflection part 12 in a space S. The firstreflection part 11 may be directly formed on the inner surface 34 a ofthe depression 34 in a support 30 without the molded layer 41 interposedtherebetween. In addition, a cover 50 may have a configurationillustrated in FIG. 3 and FIG. 4.

According to the spectrometer 1B configured as described above, it ispossible to attempt miniaturization while suppressing a decrease indetection accuracy due to a similar reason to that in theabove-described spectrometer 1A. Further, in the spectrometer 1B, thefirst reflection part 11 is the concave mirror. In this way, a spreadangle of the light L1 is suppressed by the first reflection part 11, andthus the entrance NA of the light L1 passing through a light passingpart 21 may be increased to increase sensitivity, and the length of anoptical path from a dispersive part 40 to a light detection part 22 maybe further decreased to further miniaturize the spectrometer 1B. Detailsthereof are described below. That is, when the first reflection part 11is the concave mirror, the dispersive part 40 is irradiated with thelight L1 while the light L1 is approximately collimated. For thisreason, a distance at which the dispersive part 40 concentrates light L2on the light detection part 22 is short when compared to a case in whichthe dispersive part 40 is irradiated with the light L1 while the lightL1 spreads. Therefore, the entrance NA of the light L1 may be increasedto increase sensitivity, and the optical path length from the dispersivepart 40 to the light detection part 22 may be further decreased tofurther miniaturize the spectrometer 1B.

Third Embodiment

As illustrated in FIGS. 7 and 8, a spectrometer 1C is mainly differentfrom the above-described spectrometer 1A in that a space S is airtightlysealed by a package 60B that accommodates a light detection element 20and a support 30. The package 60B includes a stem 61 and a cap 62. Forexample, the stem 61 is formed in a disc shape using metal. For example,the cap 62 is formed in a cylindrical shape using metal. The stem 61 andthe cap 62 are airtightly joined to each other while a flange part 61 aprovided on an outer edge of the stem 61 and a flange part 62 a providedat an opening end of the cap 62 are in contact with each other. By wayof example, the stem 61 and the cap 62 are airtightly sealed to eachother in a nitrogen atmosphere under dew point management (e.g., at −55°C.) or an atmosphere subjected to vacuum drawing.

A light entrance part 63 is provided on a wall part 62 b of the cap 62opposing the stem 61 to oppose a light passing part 21 of a lightdetection element 20 in a Z-axis direction. The light entrance part 63is configured by airtightly joining a window member 64 to an innersurface of the wall part 62 b to cover a light transmission hole 62 cformed in the wall part 62 b. The light transmission hole 62 c has ashape including the light passing part 21 when viewed in the Z-axisdirection. For example, the window member 64 is formed in a plate shapeusing a material which transmits light L1 therethrough, examples ofwhich include silica, borosilicate glass (BK7), Pyrex (registeredtrademark) glass, and Kovar glass. In the spectrometer 1C, the light L1enters the light passing part 21 through the light entrance part 63 fromthe outside of the package 60B. When an infrared ray is detected,silicon, germanium, etc. is effective as a material of the window member64. In addition, the window member 64 may be provided with an AR coat,and may have such a filter function as to transmit therethrough only apredetermined wavelength of light. Further, at least a portion of thewindow member 64 may be disposed inside the light transmission hole 62 csuch that an outer surface of the window member 64 and an outer surfaceof the wall part 62 b are flush with each other.

A plurality of through holes 61 b is formed in the stem 61. Lead pins 65are inserted into the respective through holes 61 b. For example, eachof the lead pins 65 is airtightly fixed to each of the through holes 61b through a hermetic seal made of sealing glass such as low-meltingglass having electrically-insulating and light-shielding properties. Anend part inside the package 60B in each of the lead pins 65 is connectedto an end part 13 b of each wiring 13 provided in the support 30 on asurface 31 b of a base wall part 31. In this way, electrical connectionbetween the lead pin 65 and the wiring 13 corresponding to each other,and positioning of the light detection element 20 and the support 30with respect to the package 60B are achieved.

The end part inside the package 60B in the lead pin 65 may be connectedto the end part 13 b of the wiring 13 extending inside a through holeformed in the base wall part 31 or inside a depression formed on thesurface 31 b of the base wall part 31 while being disposed inside thethrough hole or inside the depression. In addition, the end part insidethe package 60B in the lead pin 65 and the end part 13 b of the wiring13 may be electrically connected to each other through a circuit boardon which the support 30 is mounted by bump bonding, etc. In this case,the end part inside the package 60B in the lead pin 65 may be disposedto surround the support 30 when viewed in a thickness direction of thestem 61 (that is, the Z-axis direction). In addition, the circuit boardmay be disposed in the stem 61 while touching the stem 61, or may besupported by the plurality of lead pins 65 while being separated fromthe stem 61.

In the spectrometer 1C, for example, a substrate 24 of the lightdetection element 20 and the base wall part 31 of the support 30 areformed in hexagonal plate shapes. Further, the light detection element20 and the support 30 are accommodated in the package 60B. Thus, in thespectrometer 1C, a connection part 13 c of each wiring 13 may not beenclosed on a surface 32 b of each side wall part 32 on the space Sside, a surface 31 a of the base wall part 31, and an inner surface ofeach through hole 36 as in the above-described spectrometer 1A. In thespectrometer 1C, the connection part 13 c of each wiring 13 reaches theend part 13 b from an end part 13 a on a surface of each side wall part32 on the opposite side from the space S side and the surface 31 b ofthe base wall part 31. In this way, when the wiring 13 is enclosed on asurface of the support 30 on the opposite side from the space S side,scattering of light due to the wiring 13 exposed to the space S may beprevented. Further, in the spectrometer 1C, sealing members 15, 16, and17 may not be disposed, and a cover 50 may not be provided as in theabove-described spectrometer 1A.

According to the spectrometer 1C configured as described above, it ispossible to attempt miniaturization while suppressing a decrease indetection accuracy due to a similar reason to that in theabove-described spectrometer 1A. In addition, in the spectrometer 1C,the space S is airtightly sealed by the package 60B that accommodatesthe light detection element 20 and the support 30. In this way, it ispossible to suppress a decrease in detection accuracy resulting fromdeterioration of a member in the space S due to moisture, occurrence ofcondensation in the space S due to a decrease in ambient temperature,etc.

In addition, in the spectrometer 1C, a gap is formed among an endsurface 32 a of each side wall part 32 of the support 30, an end surface33 a of each side wall part 33, and a surface 24 a of the substrate 24of the light detection element 20. In this way, deformation of the lightdetection element 20 rarely affects the support 30, and deformation ofthe support 30 rarely affects the light detection element 20, and thusan optical path from the light passing part 21 to the light detectionpart 22 may be accurately maintained.

In addition, in the spectrometer 1C, the support 30 is supported by theplurality of lead pins 65 while being separated from the stem 61. Inthis way, deformation of the stem 61, an external force from the outsideof the package 60B, etc. rarely affect the support 30, and thus theoptical path from the light passing part 21 to the light detection part22 may be accurately maintained.

Fourth Embodiment

As illustrated in FIGS. 9 and 10, a spectrometer 1D is mainly differentfrom the spectrometer 1C in that a first reflection part 11 is a concavemirror. In the spectrometer 1D, the first reflection part 11, isprovided in a spherical region on an inner surface 34 a of a depression34 of a base wall part 31 with a molded layer 41 interposedtherebetween. For example, the first reflection part 11 is a concavemirror made of a metal evaporated film of Al, Au, etc., and reflectslight L1 passing through a light passing part 21 to a second reflectionpart 12 in a space S.

According to the spectrometer 1D configured as described above, it ispossible to attempt miniaturization while suppressing a decrease indetection accuracy due to a similar reason to that in theabove-described spectrometer 1A. Further, in the spectrometer 1D, thefirst reflection part 11 is the concave mirror. In this way, a spreadangle of the light L1 is suppressed by the first reflection part 11, andthus the entrance NA of the light L1 passing through the light passingpart 21 may be increased to increase sensitivity, and the length of anoptical path from a dispersive part 40 to a light detection part 22 maybe further decreased to further miniaturize the spectrometer 1B. Inaddition, in the spectrometer 1D, the space S is airtightly sealed by apackage 60B that accommodates a light detection element 20 and a support30. In this way, it is possible to suppress a decrease in detectionaccuracy resulting from deterioration of a member in the space S due tomoisture, occurrence of condensation in the space S due to a decrease inambient temperature, etc.

[Relationship Between Miniaturization of Spectrometer and Radius ofCurvature of Dispersive Part]

As illustrated in FIG. 11, in a spectrometer of FIG. 11(a) and aspectrometer of FIG. 11(b), light L1 passing through a light passingpart 21 directly enters a dispersive part 40, and light L2 dispersed andreflected by the dispersive part 40 directly enters a light detectionpart 22. In a spectrometer of FIG. 11(c), the light L1 passing throughthe light passing part 21 is reflected by a first reflection part 11 anda second reflection part 12 in sequence, and enters the dispersive part40, and the light L2 dispersed and reflected by the dispersive part 40directly enters the light detection part 22. In the spectrometer of FIG.11(a), the radius of curvature of an inner surface 34 a on which thedispersive part 40 is formed is 6 mm. In the spectrometer of FIG. 11(b),the radius of curvature of the inner surface 34 a on which thedispersive part 40 is formed is 3 mm. In the spectrometer of FIG. 11(c),the radius of curvature of the inner surface 34 a on which the firstreflection part 11 and the dispersive part 40 are formed is 4 mm.

First, the spectrometer of FIG. 11(a) and the spectrometer of FIG. 11(b)are compared. The height (height in a Z-axis direction) of thespectrometer of FIG. 11(b) is lower than the height of the spectrometerof FIG. 11(a) since a distance at which the dispersive part 40concentrates the light L2 on the light detection part 22 becomes shorteras the radius of curvature of the inner surface 34 a on which thedispersive part 40 is formed becomes smaller.

However, as the radius of curvature of the inner surface 34 a on whichthe dispersive part 40 is formed is made smaller, various problems occuras below. That is, a focus line of the light L2 (a line connectingpositions on which the light L2 having different wavelengths isconcentrated) is easily distorted. In addition, influence of variousaberrations becomes great, and thus there is difficulty in makingcorrection by designing a grating. Further, in particular, the angle ofdiffraction to a long wavelength side becomes excessive, and thus agrating pitch needs to be narrowed. However, when the grating pitchbecomes narrow, there is difficulty in forming a grating. Furthermore,blazing is necessary to increase sensitivity. However, when the gratingpitch is narrowed, there is difficulty in blazing. In addition, inparticular, the angle of diffraction to the long wavelength side becomesexcessive, and thus it is disadvantageous in terms of resolving power ofthe light L2.

The above-mentioned various problems occur since it is practical toconfigure the light passing part 21 such that the light L1 passes in adirection perpendicular to surfaces 24 a and 24 b of a substrate 24 of alight detection element 20 when the light passing part 21 is provided asa slit on the substrate 24. In addition, the problems occur since thereis a restriction that zero-order light L0 should be reflected on theopposite side to the light detection part 22 side.

On the other hand, in the spectrometer of FIG. 11(c), even though theradius of curvature of the inner surface 34 a on which the firstreflection part 11 and the dispersive part 40 are formed is 4 mm, theheight of the spectrometer of FIG. 11(c) is lower than the height of thespectrometer of FIG. 11(b) since an incident direction of the light L1entering the dispersive part 40 and a divergence or convergence state ofthe light L1 may be adjusted using the first reflection part 11 and thesecond reflection part 12 in the spectrometer of FIG. 11(c).

As described in the foregoing, it is practical to configure the lightpassing part 21 such that the light L1 passes in the directionperpendicular to the surfaces 24 a and 24 b of the substrate 24 of thelight detection element 20 when the light passing part 21 is provided asa slit on the substrate 24. In this case, when the first reflection part11 and the second reflection part 12 are used, miniaturization of thespectrometer may be attempted. In the spectrometer of FIG. 11(c), thefact that the zero-order light L0 can be captured by a zero-order lightcapture part 23 which is positioned between the second reflection part12 and the light detection part 22 is a great feature in attemptingminiaturization of the spectrometer while suppressing a decrease indetection accuracy of the spectrometer.

[Superiority in Optical Path from Dispersive Part to Light DetectionPart]

First, a spectrometer will be examined. Here, as illustrated in FIG. 12,the spectrometer adopts an optical path that reaches a light detectionpart 22 from a light passing part 21 via a first reflection part 11, adispersive part 40, and a second reflection part 12 in sequence. In thespectrometer of FIG. 12, light L1 is dispersed and reflected by thedispersive part 40 which is a planar grating. Then, light L2 dispersedand reflected by the dispersive part 40 is reflected by the secondreflection part 12 which is a concave mirror, and enters the lightdetection part 22. In this case, respective rays of the light L2 enterthe light detection part 22 such that positions, on which the respectiverays of the light L2 are concentrated, are close to one another.

In the spectrometer of FIG. 12, when a wavelength range of detectedlight L2 is attempted to be widened, the radius of curvature of theinner surface 34 a on which the dispersive part 40 is formed and adistance between the second reflection part 12 and the light detectionpart 22 need to be increased. Further, since the respective rays of thelight L2 enter the light detection part 22 such that positions, on whichthe respective rays of the light L2 are concentrated, are close to oneanother, the radius of curvature of the inner surface 34 a and thedistance between the second reflection part 12 and the light detectionpart 22 need to be increased. When a distance between the positions, onwhich the respective rays of the light L2 are concentrated, isexcessively widened by narrowing a grating pitch (a distance betweengrating grooves), there is difficulty in adjusting a focus line of thelight L2 to the light detection part 22. In this way, the optical path,which reaches the light detection part 22 from the light passing part 21via the first reflection part 11, the dispersive part 40, and the secondreflection part 12 in sequence, can be regarded as an unfit optical pathfor miniaturization.

On the other hand, as illustrated in FIG. 11(c), in the spectrometerthat adopts an optical path that reaches the light detection part 22from the light passing part 21 via the first reflection part 11, thesecond reflection part 12, and the dispersive part 40 in sequence (thatis, a spectrometer corresponding to the spectrometers 1A to 1D describedabove), respective rays of light L2 enter the light detection part 22such that positions, on which the respective rays of the light L2 areconcentrated, are separated from one another. Therefore, the opticalpath that reaches the light detection part 22 from the light passingpart 21 via the first reflection part 11, the second reflection part 12,and the dispersive part 40 in sequence can be regarded as a suitableoptical path for miniaturization. The above description can beunderstood from the fact that the radius of curvature of the innersurface 34 a is 4 mm, and the height (height in the Z-axis direction) isabout 2 mm in the spectrometer of FIG. 11(c) while the radius ofcurvature of the inner surface 34 a is 12 mm, and the height is 7 mm inthe spectrometer of FIG. 12.

Hereinbefore, the first to fourth embodiments of the invention have beendescribed. However, the invention is not restricted to the aboverespective embodiments. For example, even though the entrance NA of thelight L1 entering the space S is defined by the shapes of the lightpassing part 21 of the light detection element 20 and the lighttransmitting opening 52 a of the light shielding film 52 (the lighttransmitting opening 53 a of the light shielding film 53 depending oncases) in the first and second embodiments, the entrance NA of the lightL1 entering the space S may be practically defined by adjusting a shapeof a region of at least one of the first reflection part 11, the secondreflection part 12, and the dispersive part 40. The light L2 enteringthe light detection part 22 is diffracted light, and thus the entranceNA may be practically defined by adjusting a shape of a predeterminedregion in which the grating pattern 41 a is formed in the molded layer41.

In addition, even though the terminal 25 of the light detection element20 and the end part 13 a of the wiring 13 opposing each other areconnected to each other by the bump 14 in the above respectiveembodiments, the terminal 25 of the light detection element 20 and theend part 13 a of the wiring 13 opposing each other may be connected toeach other by soldering. Further, the terminal 25 of the light detectionelement 20 and the end part 13 a of the wiring 13 opposing each othermay be connected to each other on the end surface 33 a of each side wallpart 33 of the support 30 rather than only on the end surface 32 a ofeach side wall part 32 of the support 30. Alternatively, the terminal 25and the end part 13 a may be connected to each other on the end surface32 a of each side wall part 32 and the end surface 33 a of each sidewall part 33 of the support 30. Furthermore, in the spectrometers 1A and1B, the wiring 13 may be enclosed on a surface on the opposite side fromthe space S side in the support 30. In addition, in the spectrometers 1Cand 1D, the wiring 13 may be enclosed on a surface on the space S sidein the support 30.

In addition, the material of the support 30 is not restricted toceramic, and another molding material, for example, resin such as LCP,PPA, and epoxy, and glass for molding may be used as the material.Further, the package 60B may have a shape of a rectangularparallelepiped box. Furthermore, when the space S is airtightly sealedby the package 60B that accommodates the light detection element 20 andthe support 30, the support 30 may have a plurality of pillar parts or aplurality of side wall parts separated from one another in place of thepair of side wall parts 32 and the pair of side wall parts 33 whichsurround the space S. In this way, materials and shapes of respectivecomponents of the spectrometers 1A to 1D are not restricted to theabove-described materials and shapes, and various materials and shapesmay be applied thereto.

INDUSTRIAL APPLICABILITY

The invention can provide a spectrometer which can attemptminiaturization while suppressing a decrease in detection accuracy, anda method for manufacturing a spectrometer capable of easilymanufacturing such a spectrometer.

REFERENCE SIGNS LIST

1A, 1B, 1C, 1D: spectrometer; 11: first reflection part; 12: secondreflection part; 13: wiring; 13 a: end part; 20: light detectionelement; 21: light passing part; 22: light detection part; 23:zero-order light capture part; 25: terminal; 30: support; 40: dispersivepart; 60A, 60B: package; S: space; RL: reference line.

1-10. (canceled)
 11. A spectrometer comprising: a light passing part; alight detection element provided with a light detection part; a supportfixed to the light detection element such that a space is formed betweenthe light passing part and the light detection part; a first reflectionpart provided in the support and configured to reflect light passingthrough the light passing part in the space; a second reflection partconfigured to reflect the light reflected by the first reflection partin the space; and a dispersive part provided in the support andconfigured to disperse and reflect the light reflected by the secondreflection part to the light detection part in the space.
 12. Thespectrometer according to claim 11, wherein the light passing part, thefirst reflection part, the second reflection part, the dispersive part,and the light detection part are arranged along a reference line whenviewed in an optical axis direction of the light passing through thelight passing part, the dispersive part has a plurality of gratinggrooves arranged along the reference line, and the light detection parthas a plurality of light detection channels arranged along the referenceline.
 13. The spectrometer according to claim 11, wherein the firstreflection part is a planar mirror.
 14. The spectrometer according toclaim 11, wherein the first reflection part is a concave mirror.
 15. Thespectrometer according to claim 11, further comprising a zero-orderlight capture part configured to capture zero-order light in the lightdispersed and reflected by the dispersive part.
 16. The spectrometeraccording to claim 11, wherein the support is provided with a wiringelectrically connected to the light detection part, and an end part ofthe wiring on a side of the light detection part is connected to aterminal provided in the light detection element in a fixed part of thelight detection element and the support.
 17. The spectrometer accordingto claim 11, wherein a material of the support is ceramic.
 18. Thespectrometer according to claim 11, wherein the space is airtightlysealed by a package including the light detection element and thesupport as components.
 19. The spectrometer according to claim 11,wherein the space is airtightly sealed by a package accommodating thelight detection element and the support.
 20. The spectrometer accordingto claim 11, wherein the dispersive part is curved in a concave shape.21. The spectrometer according to claim 20, wherein the first reflectionpart is curved in a concave shape.
 22. The spectrometer according toclaim 11, wherein the dispersive part is provided on a curved surfacethat is curved in a concave shape in the support.
 23. The spectrometeraccording to claim 22, wherein the first reflection part is provided onthe curved surface.